Pressure cylinder in the form of a hollow cylinder made of metal

ABSTRACT

An impression cylinder in the form of a hollow cylinder made of metal, e.g., aluminum, for printing machines, having an essentially constant wall thickness over its length. The cylinder may have a predetermined inner diameter and may have various different outer diameters. The hollow cylinder includes a cylinder jacket. The cylinder jacket is provided with longitudinal openings, such as longitudinal bores. The employment of these longitudinal openings, e.g., bores, in various different numbers, sizes and shapes, enables impression cylinders having different external diameters and equal internal diameters to have substantially similar weights or mass per unit length.

FIELD OF THE INVENTION

The present invention relates to an impression cylinder in the form of ahollow cylinder made of metal, particularly of aluminum, for printingmachines, having an essentially constant wall thickness over its length.

BACKGROUND

Impression cylinders are known. In order to print different formatlengths, different cylinder outer diameters are required, which, inturn, leads to different masses and weights of the cylinders. Thesedifferences cannot be adjusted by merely reducing the wall thicknessesof the hollow cylinders, without adversely effecting the rigidity of thecylinder. On the one hand, it is important to keep the weight of theimpression cylinder as low as possible, to make handling the impressioncylinder easier for the press operator. On the other hand, for thevarious different impression cylinder outer diameters that come intouse, the differences in mass should be as low as possible, in order tokeep the boundary conditions for the drive regulation as constant aspossible.

It is an object of the present invention to create an impressioncylinder construction which addresses the various conflictingrequirements of such a device at a reasonable cost.

SUMMARY OF THE INVENTION

The present invention overcomes the above-stated disadvantages in asurprisingly simple manner. Specifically, the present invention providesan impression cylinder in the form of a hollow cylinder made of metal,particularly of aluminum, for printing machines, having an essentiallyconstant wall thickness over its length.

The hollow cylinder includes a cylinder jacket. The cylinders may havedifferent diameters. The cylinder jackets are provided with longitudinalopenings, such as longitudinal bores. The employment of theselongitudinal openings, e.g., bores, does not functionally impair therigidity of the cylinders.

The present invention enables the construction of impression cylindershaving different external diameters—with equal internal diameters so asto facilitate their use in a printing machine—which, at the same length,have essentially the same mass.

BRIEF DESCRIPTION OF THE DRAWINGS

The present invention is described below in more detail, in light of thedrawings.

FIG. 1 illustrates a longitudinal section through an impressioncylinder, in accordance with one embodiment of the present invention;and

FIGS. 2( a) to 2(c) illustrate various example bore patterns inimpression cylinders, according to several embodiments of the presentinvention.

DETAILED DESCRIPTION

FIG. 1 illustrates a longitudinal section through an impression cylinder1, according to one embodiment of the present invention. In thisembodiment, the impression cylinder 1 is made of aluminum. In addition,the impression cylinder 1 has a standardized or predetermined insidediameter D, and an outside diameter d which is variable depending on theformat length that is to be printed.

For example, in the case of a cylinder length of 350 mm and an insidediameter D of 78 mm, the outside diameter may include ranges of, forexample, 92-100, 100-120, 120-140, 140-160, 160-180 and 180-200 mm.

By virtue of longitudinal openings 2 in the impression cylinders, theweight, or mass, of an impression cylinder may be substantially similarto the weight or mass of other impression cylinders that have asubstantially similar inside diameter but a different outside diameter.More specifically, the weight or mass per unit of length of theimpression cylinder is maintained constant for various differentimpression cylinders—and in particular for impression cylinders havingsubstantially similar inside diameters but a different outside diameterdifferent—by virtue of the impression cylinders having longitudinalopenings distributed therethrough. The longitudinal openings areadvantageously straight-through longitudinal openings, e.g.,longitudinal bores 2, that are evenly or regularly, e.g., symmetrically,distributed over the circumference of the impression cylinder. Therequired rigidity of the impression cylinder is not functionallyimpaired by the longitudinal openings.

Advantageously, the longitudinal openings 2 may be provided, as shown inFIGS. 2( a) to 2(c), at one or more diameters, and advantageouslyprevent the impression cylinder from being imbalanced. In oneembodiment, this is achieved by providing longitudinal openings that areequally and oppositely angularly spaced around the circumference of theimpression cylinder, and by providing a constant cross section.

In order to provide a uniform weight or mass for different impressioncylinders having the same inside diameter of the cylinder but differentoutside diameters, the impression cylinders may have any number oflongitudinal openings. Furthermore, the longitudinal openings may haveany cross-sectional shapes, e.g., circular, and may be positioned at oneor any number of different diametric locations.

In this manner, the weight of the impression cylinder may be kept low,so as to make the impression cylinder easier to handle. Furthermore, themass of various different impression cylinders may be substantiallysimilar, so as to hold the boundary conditions for the drive controlleras constant as possible.

1. A set of impression cylinders comprising: a first impression cylinderhaving an inside diameter and an outside diameter, and having a cylinderwall defining a plurality of longitudinal openings; and a secondimpression cylinder having an inside diameter that is substantiallysimilar to the inside diameter of the first impression cylinder andhaving an outside diameter that is different from the outside diameterof the first impression cylinder, and having a cylinder wall defining aplurality of longitudinal openings, wherein the respective longitudinalopenings of the first and second impression cylinders are sized andpositioned such that the first and second impression cylinders have asubstantially similar mass per longitudinal unit of length.
 2. The setof impression cylinders according to claim 1 wherein, in at least one ofthe first and second impression cylinders: the cylinder wall has asubstantially constant wall thickness over an entire length thereof, andthe openings are located on at least one predefined diameter, whereinthe plurality of longitudinal openings each have a constant crosssection over an entire length thereof and the longitudinal openings aredistributed in the cylinder wall such that the impression cylinder issubstantially free from imbalance.
 3. The set of impression cylindersaccording to claim 2, wherein in at least one of the first and secondimpression cylinders; the hollow cylinder is made of metal.
 4. The setof impression cylinders according to claim 3, wherein in at least one ofthe first and second impression cylinders: the hollow cylinder is madeof aluminum.
 5. The set of impression cylinders according to claim 2,wherein in at least one of the first and second impression cylinders:the plurality of longitudinal openings extend the entire length of thecylinder.
 6. The set of impression cylinders according to claim 2,wherein in at least one of the first and second impression cylinders:the plurality of longitudinal openings are provided on various diametersand the longitudinal openings are arranged symmetrically to a centralaxis of the cylinder in diameter planes having the same angular spacingwith respect to one another.
 7. The set of impression cylindersaccording to claim 6, wherein in at least one of the first and secondimpression cylinders: each of the plurality of the longitudinal openingsthat are arranged at a given diameter have a similar cross-section. 8.The set of impression cylinders according to claim 2, wherein in atleast one of the first and second impression cylinders: the longitudinalopenings are bores having a circular cross section.